Instead of having to redesign certain projects, put a voltage mirror
into place. Voltage mirrors give you a copy of the input voltage,
but with the polarity swapped.

■ By Jim Stewart

32 Build the Mystery Solar Powered Pendulum

Amaze and mesmerize your friends and family with this fun
gadget that is based on BEAM technology.

■ By David Williams

36 Build the Alarm Autodialer

Not only will this device detect household failures related to
heating, cooling, plumbing, and electrical, but it will call to
let you know if anything is going on.

■ By Dan Gravatt

41 A Proper Ringing of the Bells

See the art of engineering at work when an
older system for ringing church bells needed
a makeover.

■ By Chris Watson

Page 32

46 Design a Customized Security
System Using RobotBASIC
Implementing a custom security system for
your home can be intimidating — unless you
have the right software. This article guides
you through the basic principles so you can
design exactly what will work for you.

■ By John Blankenship and Samuel Mishal

Columns

10 TechKnowledgey 2012

Events, Advances, and News

Read about a new PC for bottom-feeders,
an automotive mystery that gets solved, the vacuum
tube as the next high tech breakthrough ... plus
some other interesting stuff.